Allāh, the Most High, stated:
وَقَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ ۚ إِنَّ الَّذِينَ يَسْتَكْبِرُونَ عَنْ عِبَادَتِي سَيَدْخُلُونَ جَهَنَّمَ دَاخِرِينَ
“And your Lord has said, ‘Call upon Me, and I will respond to you.’ Indeed, those who disdain My worship will enter Hell in disgrace.” (Ghāfir 40:60)
ادْعُوا رَبَّكُمْ تَضَرُّعًا وَخُفْيَةً ۚ إِنَّهُ لَا يُحِبُّ الْمُعْتَدِينَ
“Call upon your Lord in humility and in secret. Indeed, He likes not those who transgress beyond bounds.” (Al-A’rāf 7:55)
وَإِذَا سَأَلَكَ عِبَادِي عَنِّي فَإِنِّي قَرِيبٌ ۖ أُجِيبُ دَعْوَةَ الدَّاعِ إِذَا دَعَانِ ۖ فَلْيَسْتَجِيبُوا لِي وَلْيُؤْمِنُوا بِي لَعَلَّهُمْ يَرْشُدُونَ
“And when My servants ask you, O Muhammad, concerning Me, then indeed I am near. I respond to the invocation of the supplicant when he calls upon Me. So let them respond to Me in obedience, and believe in Me that they may be rightly guided.” (Al-Baqarah 2:186)
أَمَّن يُجِيبُ الْمُضْطَرَّ إِذَا دَعَاهُ وَيَكْشِفُ السُّوءَ وَيَجْعَلُكُمْ خُلَفَاءَ الْأَرْضِ ۗ أَإِلَٰهٌ مَّعَ اللَّهِ ۚ قَلِيلًا مَّا تَذَكَّرُونَ
“Is He not best, the One who responds to the desperate one when he calls upon Him and removes evil and makes you inheritors of the earth? Is there a deity with Allāh? Little do you remember.” (An-Naml 27:62)
Points from the explanation of Shaikh Muhammad Ibn Sālih Al-‘Uthaimīn (with explanatory additions and narrations from Abu Khadeejah):
An-Nawawī (rahimahullāh) has a chapter in his Riyād As-Sālihīn called ‘The Book of Invocations (Arabic: Da’wāt)’. The singular is da’wah, and that is the invocation that a person makes to his Lord (the Most High). So a person will invoke Allah saying, “My Lord” or similar terms. Through this invocation, he asks Allāh (the Most High) to confer upon him what he seeks and to remove from him what he does not desire. Then An-Nawawī (rahimahullāh) mentions the chapter: The command to supplicate and its virtues. As for verse:
ادْعُونِي أَسْتَجِبْ لَكُمْ
“Call upon Me, and I will respond to you.” This is the command of Allāh followed by His promise, and Allāh never breaks His promise:
ۚ إِنَّ اللَّهَ لَا يُخْلِفُ الْمِيعَادَ
“Verily, Allah never breaks His Promise.” (Āli ‘Imrān 3:9)
So this is a command to perform the supplication of worship , and the supplication of seeking  from Allāh.
As for the supplication of worship, then it is that a person establishes the worship of Allāh. That is because if you ask the one who establishes the various acts of worship: Why do you perform the Salāh? Why do you pay the Zakāh? Why do you fast? Why do you perform Hajj? Why do you strive in Allāh’s cause? Why are you kind and dutiful to your parents? Why do maintain the family ties? He will surely say, “I intend by these acts to seek the pleasure of Allāh.” So these deeds of worship comprise invocation (du’ā).
The intent is that a person worships Allāh with various deeds of devotion, whether it it be with the limbs such as the Salāh, or with one’s wealth such as giving charity, or with one’s heart such as fear and love, or with one’s tongue such as reciting the Qur’ān, praising and glorifying Allāh.
As for the supplication of seeking, then it is when you ask for something from Allāh. So, for example, you would say, “O Lord, forgive me”, “O my Lord, be merciful with me”, “O my Lord, provide for me” and so on. This too is worship just as the Prophet (ﷺ) said, “Supplication is worship.” (At-Tirmidhī no. 3247) It is worship due to the fact that one turns to Allāh (ﷻ) in seeking, and acknowledges His bounty. So the saying of Allāh:
ادْعُونِي أَسْتَجِبْ لَكُمْ
“Call upon Me, and I will respond to you” includes both the supplication of worship and the supplication of seeking. So the response of Allāh as it relates to the worship one performs, then it is His acceptance of that worship. As for His response as it relates to one asking Allāh for something, is that He gives the person what he asks for. And this is a promise from Allāh, the Most High. However, there are conditions for one’s supplications to be answered.
The Conditions for a Du’ā to be accepted:
First condition: Sincerity. One must sincerely and purely direct his supplication to Allāh alone without associating partners with Him. He must not worship to show-off to the people or to seek fame. He must not perform Hajj, for example, so that it he wants others to say, “He is Al-Hājj (or Hājī),” or give in charity so that he wants people to say, “He is generous and bountiful,” or to fast in desire of the people’s praise of him, “Look how often he fasts.” If one performs his deeds seeking praise from the people, his deed is nullified. Likewise, when supplicating to Allāh for something that you want from Him, you must seek it from Him sincerely. Call upon Allāh whilst you are aware of the fact that you are in need of Allāh, and that He is free of any need of you, and He is fully able to give you what you seek from Him.
Second condition: The supplication must not contain any sin and transgression. If the supplication is sinful, then it will not be accepted by Allāh, even if the father supplicates against his own children, or the mother supplicates against her own children. Allāh does not accept supplications that transgress against others. Allāh, the Most High said:
ادْعُوا رَبَّكُمْ تَضَرُّعًا وَخُفْيَةً ۚ إِنَّهُ لَا يُحِبُّ الْمُعْتَدِينَ
“Call upon your Lord in humility and in secret. Indeed, He likes not those who transgress beyond bounds.” (Al-A’rāf 7:55) So if a person supplicates seeking something sinful such as asking for a thing which is prohibited in the Religion, it will not be accepted because it is transgressing the bounds. If one asked Allāh, “O Allāh, make me a Prophet”, then this not permitted and is transgressing beyond bounds and is not accepted by Allāh. If a person was to supplicate against the one he has oppressed, it will not be accepted. If a mother was to supplicate against her own son because he loves his wife, it will not be accepted. If a father was to supplicate against his son because he accompanies pious and good people, then it will not be accepted. So the supplication must not contain a request to sin or to transgress the bounds of the Sharī’ah.
The Prophet (ﷺ) said, “A person’s supplication will be answered provided he does not ask for what is sinful or the severing of family ties, and he must not be hasty/impatient.” He was asked, “What is impatience, O Allah’s Messenger?” He replied, “That the person says, ‘I supplicated, but my supplication was not answered’. So he becomes disappointed and abandons supplicating.” (Muslim)
Third Condition: A person should supplicate to Allāh whilst being certain of a response, not just making an attempt to see if it works. Some people supplicate to try it out, to see if it will be accepted or not. This type of supplication is not accepted. Call upon Allāh whilst you are certain that He, the Most High, will respond to you. And if you supplicate to Allāh whilst you are doubtful, Allāh will not accept such a supplication.
The Prophet (ﷺ) said, “Ask Allāh whilst you are certain of His response and know that Allah does not accept the supplication of the neglectful and distracted heart.” (At-Tirmidhī, see As-Sahīhah of Al-Albānī, no. 594)
He also said, “The one who likes that Allāh should answer him in at the time of adversity and hardship, let him increase in supplicating in times of ease.” (Tirmidhi)
Fourth Condition: A person must abandon what is prohibited by Allāh, such that he does not eat what is forbidden, or consume usury, or wealth obtained through trickery or deception, and so on. The supplication of such a person is not accepted. The evidence for this is the saying of the Prophet (ﷺ):
أَيُّهَا النَّاسُ إِنَّ اللَّهَ طَيِّبٌ لاَ يَقْبَلُ إِلاَّ طَيِّبًا وَإِنَّ اللَّهَ أَمَرَ الْمُؤْمِنِينَ بِمَا أَمَرَ بِهِ الْمُرْسَلِينَ
“O people, indeed Allāh is good, and He does not accept except what is good. Verily, Allāh commanded the believers with that which He commanded the Messengers. Allāh, the Most High, said:
يَا أَيُّهَا الرُّسُلُ كُلُوا مِنَ الطَّيِّبَاتِ وَاعْمَلُوا صَالِحًا إِنِّي بِمَا تَعْمَلُونَ عَلِيمٌ
“O, Messengers! Eat of the good foods which Allāh has made permissible, and do righteous deeds. Verily! I am Well-Acquainted with what you do.” (Al-Mu’minūn 23:51) And He, the Most High, said:
يَا أَيُّهَا الَّذِينَ آمَنُوا كُلُوا مِنْ طَيِّبَاتِ مَا رَزَقْنَاكُمْ
“O you who believe, eat the good things that We have provided for you.” (Al-Baqarah 2:172)
ثُمَّ ذَكَرَ الرَّجُلَ يُطِيلُ السَّفَرَ أَشْعَثَ أَغْبَرَ يَمُدُّ يَدَيْهِ إلَى السَّمَاءِ: يَا رَبِّ! يَا رَبِّ! وَمَطْعَمُهُ حَرَامٌ، وَمَشْرَبُهُ حَرَامٌ، وَمَلْبَسُهُ حَرَامٌ، وَغُذِّيَ بِالْحَرَامِ، فَأَنَّى يُسْتَجَابُ لَهُ
Then the Prophet said: “A man travelled a long journey such that his hair is dishevelled and covered with dust – then he raises his hands to towards the sky supplicating, “O my Lord, O my Lord…” Yet his food is unlawful, his drink is unlawful, his clothes are unlawful and his sustenance is unlawful. Therefore, how can his supplication be accepted?!” (Muslim no. 1015)
The Prophet (ﷺ) made him far distant from having his supplication accepted, even though this man was worthy because he was upon a long journey, dusty and dishevelled due to it. However, due to his food, drink, earnings and clothing being unlawful he became distant from having his supplication accepted by Allāh.
So these are the four conditions of a supplication that must be present.
Supplications are answered:
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، أَنَّهُ كَانَ يَقُولُ مَا مِنْ دَاعٍ يَدْعُو إِلاَّ كَانَ بَيْنَ إِحْدَى ثَلاَثٍ إِمَّا أَنْ يُسْتَجَابَ لَهُ وَإِمَّا أَنْ يُدَّخَرَ لَهُ وَإِمَّا أَنْ يُكَفَّرَ عَنْهُ
Mālik narrated that Zayd ibn Aslam used to say, “No one makes a du’ā without one of three things happening: Either it is answered, or it is stored up for him, or sinful actions are atoned for by it.” (Muwatta Mālik, no. 508)
قال ابن عبد البر : هذا لا يكون رأيا بل توقيف وهو خبر محفوظ عن النبي ، صلى الله عليه وسلم ، ثم أخرج عن جابر أن النبي ، صلى الله عليه وسلم ، قال : دعاء المسلم بين إحدى ثلاث : إما أن يعطى مسألته التي سأل ، أو يرفع بها درجة ، أو يحط بها عنه خطيئة ، ما لم يدع بقطيعة رحم أو مأثم أو يستعجل
Ibn Abdul-Barr said: This is not merely his opinion, rather it from a Companion and a narrated recorded from the Prophet (ﷺ). Jābir narrated from the Prophet (ﷺ) that he said, “The supplication (du’ā) of the Muslim is between one of three affairs: Either he is given what he asked for, or due to it he is raised in rank, or because of it his sins are wiped away, so long as he does not supplicate for cutting close family ties, or supplicate seeking sin, and he is not hasty.”
قال : وأخرج ابن جرير وابن أبي شيبة عن أبي سعيد قال ، صلى الله عليه وسلم : إن دعوة المسلم لا ترد ما لم يدع بإثم أو قطيعة رحم ، إما أن تعجل له في الدنيا ، وإما أن تدخر له في الآخرة ، وإما أن يصرف عنه من السوء بقدر ما دعاه
Ibn Abdul-Barr also said: Ibn Jarīr, Ibn Abī Shaybah report from Sa’īd that Allah’s Messenger (ﷺ) said, “The supplication of a Muslim is not refused so long as he does not supplicate for a sin, or for cutting family ties. So either he will receive what he asked for in this world, or it will be stored up for him in the Hereafter, or otherwise, evil and harm will be turned away from him according to the extent he supplicated.”
مَا مِنْ رَجُلٍ يَدْعُو اللَّهَ بِدُعَاءٍ إِلاَّ اسْتُجِيبَ لَهُ فَإِمَّا أَنْ يُعَجَّلَ لَهُ فِي الدُّنْيَا وَإِمَّا أَنْ يُدَّخَرَ لَهُ فِي الآخِرَةِ وَإِمَّا أَنْ يُكَفَّرَ عَنْهُ مِنْ ذُنُوبِهِ بِقَدْرِ مَا دَعَا مَا لَمْ يَدْعُ بِإِثْمٍ أَوْ قَطِيعَةِ رَحِمٍ أَوْ يَسْتَعْجِلُ ” . قَالُوا يَا رَسُولَ اللَّهِ وَكَيْفَ يَسْتَعْجِلُ قَالَ ” يَقُولُ دَعَوْتُ رَبِّي فَمَا اسْتَجَابَ لِي
The Abu Hurairah narrated that the Messenger of Allah (ﷺ) said: “There is not a man who calls upon Allah with a supplication, except that he is answered: Either it shall be granted to him in the world, or reserved for him in the Hereafter, or his sins shall be expiated due to it according to the extent that he supplicated – as long as he does not supplicate for some sin, or for the severing of the ties of kinship, and he does not become hasty.” They said: “O Messenger of Allah, and how would he be hasty?” He (ﷺ) said: “He says: ‘I called upon my Lord, but He did not answer me.’” (At-Tirmidhī, no. 3604/3(m) Al-Albānī said: Saheeh except for the part: ‘or his sins shall be expiated due to it according to the extent that he supplicated’.)
Abu Hurairah narrated from Allah’s Messenger (ﷺ) that he said, “There is not a servant who raises his hands such that his armpits become visible, and then he asks Allah for something, except that Allah will give it to him, so long as he is not hasty/impatient.” They asked, “How is one hasty?” He replied, “He says, ‘I asked and I asked but I was not given anything’.”(At-Tirmidhī no. 3604/4(m) Al-Albānī said saheeh dūna raf’)
Abu Hurairah narrated that Allah’s Messenger (ﷺ) said
يَنْزِلُ اللَّهُ إِلَى السَّمَاءِ الدُّنْيَا كُلَّ لَيْلَةٍ حِينَ يَمْضِي ثُلُثُ اللَّيْلِ الأَوَّلُ فَيَقُولُ أَنَا الْمَلِكُ أَنَا الْمَلِكُ مَنْ ذَا الَّذِي يَدْعُونِي فَأَسْتَجِيبَ لَهُ مَنْ ذَا الَّذِي يَسْأَلُنِي فَأُعْطِيَهُ مَنْ ذَا الَّذِي يَسْتَغْفِرُنِي فَأَغْفِرَ لَهُ فَلاَ يَزَالُ كَذَلِكَ حَتَّى يُضِيءَ الْفَجْرُ
“Allah descends to the sky of the earth each night when one-third of the first part of the night is over and says: I am the King, I am the King. Who is there to supplicate to Me so that I may answer him? Who is there to ask Me so that I may grant him? Who is there to beg forgiveness from Me so that I may forgive him? He continues like this till the dawn breaks.” (Muslim, no. 758)
عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ” يَقُولُ اللَّهُ عَزَّ وَجَلَّ أَنَا عِنْدَ ظَنِّ عَبْدِي بِي وَأَنَا مَعَهُ حِينَ يَذْكُرُنِي فَإِنْ ذَكَرَنِي فِي نَفْسِهِ ذَكَرْتُهُ فِي نَفْسِي وَإِنْ ذَكَرَنِي فِي مَلإٍ ذَكَرْتُهُ فِي مَلإٍ خَيْرٍ مِنْهُمْ وَإِنِ اقْتَرَبَ إِلَىَّ شِبْرًا اقْتَرَبْتُ مِنْهُ ذِرَاعًا وَإِنِ اقْتَرَبَ إِلَىَّ ذِرَاعًا اقْتَرَبْتُ إِلَيْهِ بَاعًا وَإِنْ أَتَانِي يَمْشِي أَتَيْتُهُ هَرْوَلَةً ” . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ . وَيُرْوَى عَنِ الأَعْمَشِ فِي تَفْسِيرِ هَذَا الْحَدِيثِ مَنْ تَقَرَّبَ مِنِّي شِبْرًا تَقَرَّبْتُ مِنْهُ ذِرَاعًا يَعْنِي بِالْمَغْفِرَةِ وَالرَّحْمَةِ وَهَكَذَا فَسَّرَ بَعْضُ أَهْلِ الْعِلْمِ هَذَا الْحَدِيثَ . قَالُوا إِنَّمَا مَعْنَاهُ يَقُولُ إِذَا تَقَرَّبَ إِلَىَّ الْعَبْدُ بِطَاعَتِي وَمَا أَمَرْتُ أُسْرِعُ إِلَيْهِ بِمَغْفِرَتِي وَرَحْمَتِي .
Abu Hurairah [may Allah be pleased with him] narrated that the Messenger of Allah (ﷺ) said: “Allah, the Most High, said: ‘I am as My slave thinks of Me, and I am with him when he remembers Me. If he remembers Me to himself, I remember him to Myself, and if he remembers Me in a gathering, I remember him in a gathering better than that. And if he seeks to draw nearer to Me by a hand span, I draw nearer to him by a forearm’s length, and if he comes to Me by a forearm’s length, I draw nearer to him by an arm’s length. And if he comes to Me walking, I come to him quickly.’” It has been reported from Al-A’mash in his tasfeer of this hadeeth: “If he seeks to draw nearer to Me by a hand span, I draw nearer to him by a forearm’s length,” meaning in forgiveness and mercy. This is how some of the scholars have explained this hadeeth. They said: Its meaning is that He says: “If a servant draws close to Me in obedience of Me, I will be quick to bring to him My Forgiveness and My Mercy.” (At-Tirmidhī no. 3603 and Al-Albānī declared it saheeh).
1. Arabic: Du’ā Al-‘Ibādah.
2. Arabic: Du’ā Al-Mas’alah.